1. Field of the Invention
The invention relates to liquid droplet discharging apparatuses, e.g., ink-jet printers, and liquid cartridges, e.g., ink cartridges, to be used with liquid droplet discharging apparatuses.
2. Description of Related Art
In a known ink-jet printer, ink is supplied from an ink cartridge to a discharging head and then discharged from a plurality of nozzles formed in the discharging head, such that an image is printed on a sheet of paper. When gas is dissolved in ink in the ink cartridge, the gas may form gas bubbles, and the gas bubbles may be supplied to the discharging head together with ink. As a consequence, the gas bubbles may cause a discharge failure in the nozzles, thereby lowering the printing quality. In order to prevent gas bubbles from forming, when the ink cartridge is manufactured, gas dissolved in the ink is discharged to an exterior of the ink cartridge by depressurizing an ink chamber of the ink cartridge, such that the pressure of the ink chamber is less than the atmospheric pressure. The ink cartridge is packed and shipped in this depressurized state. A similar method is described in JP-A-2007-144804, for example.
When an ink cartridge is mounted to an ink-jet printer, if the ink chamber is brought into communication with the discharging head while the ink chamber is still in a depressurized state, a reverse flow of ink from the discharging head toward the ink cartridge may occur, and air may enter the discharging head through the nozzles. As a result, menisci of ink formed in the nozzles of the discharging head are destroyed, and ink no longer may be discharged stably. To prevent this, the ink cartridge has an air communication valve, in addition to an ink supply valve. When opened, the air communication valve permits the pressure of the interior of the ink chamber to equalize with the atmospheric pressure. During a mounting operation, when the ink cartridge is mounted to the printer, the air communication valve is opened before the ink supply valve is opened, in order to equalize the pressure and prevent a reverse flow of ink from the discharging head toward the ink cartridge.
Nevertheless, when a user mounts the ink cartridge to the printer quickly, the period of time between opening the air communication valve and opening the ink supply valve may be short, and the pressure of the ink chamber may not have sufficient time to equalize with the atmospheric pressure. Hence, the ink chamber may be brought into communication with the discharging head before the pressure in the ink chamber reaches the atmospheric pressure. Accordingly, the menisci of ink formed in the nozzles of the discharging head may be destroyed, and ink no longer may be discharged stably.